Consumer groups have urged customers of energy supplier Ovo not to panic after rival E.On announced plans to buy the company.
All existing tariffs will be honoured in full and their gas and electricity service will be unaffected under the planned deal, consumer group Which? said.
The takeover is set to create one of Britain's largest energy suppliers, vying with Octopus for the top spot.
E.On, which has 5.6 million customers, and Ovo, with four million customers, will continue to operate separately before any decision on a deal being approved, which could come later this year.
The value of the deal has not been disclosed, though previous reports have estimated it could be worth as much as £600m. The takeover will be checked by regulators, before any approval is granted.
